Hi
I left my computer on when I had to go out of station just for a day or so. So when I returned I see this pop up on screen and I click cancel. Its a "windows cannot open this file" popup. So now whenever I reboot my system this annoying windows always comes up. What do I do?? Its irritating me. Please help its really annoying.

There, you'll find a subkey for each of the items loaded at startup.
Remove the entry corresponding to the one above.

OR

If that file and associated program is really required, then:

One such (legal) software is PTFB (Push The Freakin' Button), which, although doesn't actually eliminate those annoying software messages, will do the task of clicking or closing the box for you- The result? You can set it to close the boxes so fast (as soon as they come up) that you barely even notice them.

Another alternative is to make your own AutoHotKey script which would automatically close any popup you want:

Put the .ahk file in the startup and there you go- However, it may happen that WB could load well before the script loads, which would defeat the whole purpose. You may however, remove WB's entry from the startup and make the script launch WB instead, like this:
Run, C:\Program Files\Stardock\Object Desktop\WindowBlinds\wbload.exe,
C:\Program Files\Stardock\Object Desktop\WindowBlinds

PS: Its always better to disable entries than to totally delete them as they can be used to restore the program entries incase an error occurs.